Hypersensitivity reactions to foods affect up to 6% of children in the first few years of life (Bock, S. A. 1987. Pediatrics 79:683-688), with milk, egg, and peanut accounting for most of the documented allergic responses (James J M and Sampson H A. 1992. Pediatr Allergy & Immunol 3:67-78). Most milk-allergic children develop cow milk hypersensitivity in the first year of life and then approximately 80% "outgrow" their reactivity (i.e. become clinically tolerant) by three years of age (Host, A. 1994. Pediatr Allergy Immunol 5:5-36). Hypersensitivity to hen's egg and peanut are more often recognized in the second year of life. Egg allergy appears to be more persistent than cow milk allergy whereas peanut allergy is very rarely "outgrown" (Bock, S. A. 1982. J Allergy Clin Immunol 69:173-177; Sampson, H. A. and S. M. Scanlon. 1989. J Pediatr 115:23-27; Bock, S. A. and F. M. Atkins. 1989. J Allergy Clin Immunol 83:900-904). The basis for these differences in persistence of clinical hypersensitivity to different food allergens is unknown.
Egg allergy is present in nearly two-thirds of children with atopic dermatitis (Sampson, H. A. J. 1997 Roy. Soc. Med. 90(suppl 30):3-9). When egg allergic children are placed on a diet devoid of all egg protein, about one-third develop clinical tolerance to egg within 2 years, even though IgE antibodies to egg (e.g. positive prick skin tests) persist for several years (Sampson 1989). Ovomucoid (Gal d 1) is the dominant allergen in hen's egg, and children with persistent egg allergy have significantly higher concentrations of IgE anti-ovomucoid antibodies than those who "outgrow" their reactivity (Bernhisel-Broadbent, J.,et al. 1994. J Allergy Clin Immunol 93:1047-1059). Ovomucoid is a glycoprotein comprised of 186 amino acids arranged in three tandem domains containing nine intra-domain disulfide bonds and five carbohydrate side chains (Kato, et al. 1987. Biochemistry 26:193-201).
It is an object of this invention to provide an assay including methods and reagents for predicting the likelihood that children will outgrow an allergy, especially a food allergy.
It is a further object of the present invention to provide a method and reagents to screen for the presence of antibodies to linear versus conformational epitopes in patient samples.